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1.
FRANÇOIS MUNOZ THIERRY PAILLER INGRID KOTTKE CÉDRIC GONNEAU MARC‐ANDRÉ SELOSSE 《Molecular ecology》2012,21(20):5098-5109
Characterizing the architecture of bipartite networks is increasingly used as a framework to study biotic interactions within their ecological context and to assess the extent to which evolutionary constraint shape them. Orchid mycorrhizal symbioses are particularly interesting as they are viewed as more beneficial for plants than for fungi, a situation expected to result in an asymmetry of biological constraint. This study addressed the architecture and phylogenetic constraint in these associations in tropical context. We identified a bipartite network including 73 orchid species and 95 taxonomic units of mycorrhizal fungi across the natural habitats of Reunion Island. Unlike some recent evidence for nestedness in mycorrhizal symbioses, we found a highly modular architecture that largely reflected an ecological barrier between epiphytic and terrestrial subnetworks. By testing for phylogenetic signal, the overall signal was stronger for both partners in the epiphytic subnetwork. Moreover, in the subnetwork of epiphytic angraecoid orchids, the signal in orchid phylogeny was stronger than the signal in fungal phylogeny. Epiphytic associations are therefore more conservative and may co‐evolve more than terrestrial ones. We suggest that such tighter phylogenetic specialization may have been driven by stressful life conditions in the epiphytic niches. In addition to paralleling recent insights into mycorrhizal networks, this study furthermore provides support for epiphytism as a major factor affecting ecological assemblage and evolutionary constraint in tropical mycorrhizal symbioses. 相似文献
2.
G. Pellegrino D. Caimi M. E. Noce A. Musacchio 《Plant Systematics and Evolution》2005,251(2-4):119-129
The rewardless orchid Dactylorhiza sambucina shows a stable flower colour polymorphism, with both yellow- and red-flowered morphs growing sympatrically. Pollination biology and breeding system were investigated to examine the effects of density of plants, colour polymorphism, inflorescence dimension, and flower position within inflorescence on male and female reproductive success in three natural populations of D. sambucina. There were significant differences among sites in the number of pollinia removed and in fruit set per inflorescence. Number of removed pollinia and capsule production in D. sambucina were independent from flower and inflorescence size or flower position. As a whole, the red morphs showed the highest number of capsules produced, while the yellow morphs had the greatest male success. The relative male and female reproductive success were independent from plant density but were significantly correlated with the yellow morph frequency at the population level. Overall, our findings show that the contribution to the total reproductive success deriving from the two colour morphs does not conform with the predictions of negative frequency-dependent selection. 相似文献
3.
Naoto Sugiura 《Ecological Research》1996,11(3):249-255
The behavior of visitors to the flowers of the orchidEpipactis thunbergii was studied, with special attention to the role of the epichile in the pollination process. Only four species of syrphid
flies legitimately pollinated the flower, among whichSphaerophoria macrogaster was regarded as the most effective pollinator. The movable epichile, possessing a furrow at its base, played a critical role
in the pollination process: it threw the syrphid fly onto the stigmatic surface when both sides of the basal slanting surface
of the furrow were presumably pressed in the direction of the hypochile by the fore (and middle) legs of the retreating syrphid
fly. At this moment, the fly received a set of pollinia on the thorax. 相似文献
4.
Use of VIRAZOLE® to eradicate odontoglossum ringspot virus from in vitro cultures of Cymbidium Sw. 总被引:1,自引:0,他引:1
A. Toussaint J. Kummert C. Maroquin A. Lebrun J. Roggemans 《Plant Cell, Tissue and Organ Culture》1993,32(3):303-309
Odontoglossum Ringspot Virus has been eradicated from Cymbidium Sw. through chemotherapy based on incorporation of ribavirin (VIRAZOLE®) into the in vitro culture medium of protocorms. Applications of the virustatic agent for several consecutive subcultures freed protocorms of the virus. Acclimated plantlets regenerated from those protocorms are healthy as determinated by enzyme-linked immunosorbent assay (ELISA). No resurgence of virus occurred over a period of 5 years. Besides, trueness to type was total at flowering level and the batch grown was perfectly homogeneous.To secure fast and effective eradication of the virus during the consecutive subcultures of protocorms with ribavirin, three factors proved to be of prime importance: accurate isolation of new growths from initial tissues, VIRAZOLE® concentration and frequency of transplanting in new media. 相似文献
5.
Foliar regeneration of the endangered Red Vanda,Renanthera imschootiana Rolfe (Orchidaceae) 总被引:1,自引:0,他引:1
An in vitro method was developed to regenerate large numbers of phenotypically uniform plants from the basal parts of the leaves of flowering plants of Renanthera imschootiana Rolfe. Differentiation of up to 10 shoot buds free of callus and protocorm-like bodies occurred in 10–12 weeks from the base of a single leaf implanted in Mitra et al. (1976) medium supplemented with 2% sucrose, 2 g l-1 peptone, 44.4 M benzyladenine (BA) and 10.7 M naphthaleneacetic acid (NAA). Subculture of the tissues in medium enriched with 10% coconut water and 35 g l-1 ripe banana pulp resulted in the production of highest average number of 40 shoots in 12 weeks. No difference in the regeneration potential was observed among the three young leaves while mature leaves did not respond. All the leaves of the regenerated shoots were easily recultured to increase shoot multiplication. Shoots readily formed roots on transfer to a medium containing 4.4 M BA, 10.7 M NAA and 1% activated charcoal. All regenerated plants examined were normal diploids with 2n=38. Foliar meristem culture appears to have great potential for ex situ conservation and propagation of this extremely endangered orchid.Abbreviations BA
benzyladenine
- NAA
naphthaleneacetic acid 相似文献
6.
Protocorms or protocorms with roots of an achlorophyllous orchidGaleola septentrionalis were inoculated with isolates ofRhizoctonia repens, R. solani, andRhizoctonia spp. The seedlings were infected with eight of twelve isolates ofR. repens. Fungal coils were formed in the cells, which was suggestive of a symbiotic association. The other isolates caused soft rot
or no infection to the protocorms or the protocorms with a root.
Contribution No. 97, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba,
Tsukuba, Ibaraki 305, Japan. 相似文献
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从西双版纳纳板河流域国家级自然保护区的盆距兰Gastrochilus、隔距兰Cleisostoma、毛兰Eria、贝母兰Coelogyne和万代兰Vanda的根、茎、叶分离得到172株非菌根内生真菌,根据ITS1-5.8S-ITS2 rDNA系统发育分析鉴定为盘菌亚门的4纲11目29属,其中炭角菌目、肉座菌目和格孢腔菌目真菌的相对频率最高;Xylaria、Fusarium和Phoma为主要优势属,相对频率分别为23.3%、14.5%和10.5%,它们的组织专化性不同,其中Xylaria在根、茎和叶均有分布,而Fusarium和Phoma都分离自根部。不同组织的内生真菌多样性和种类组成差异明显,根、茎和叶的内生真菌Shannon多样性指数分别为2.4083、1.0312和0.6557,表明根部内生真菌多样性显著高于茎、叶内生真菌多样性,其中根的主要优势内生真菌类群有Fusarium、Xylaria和Phoma,茎的主要优势内生真菌类群有Xylaria、Pestalotiopsis和Colletotrichum,叶的主要优势内生真菌类群有Colletotrichum、Pallidocercospora、Pantospora和Phyllosticta。从附生兰种类来看,盆距兰、隔距兰、毛兰、贝母兰和万代兰内生真菌的Shannon多样性指数分别为2.2689、2.2635、2.0115、1.9197、1.7139,表明盆距兰和隔距兰内生真菌多样性高于毛兰、贝母兰和万代兰。 相似文献